DESCRIPTION
The SC28L91 is a new member of the IMPACT family of Serial Communications Controllers. It is a single channel UART operating at 3.3 and 5.0 volts Vcc, 8 or 16 byte FIFOs and is quite compatible with software of the SC28L92 and previous UARTs offered by Philips. It is a new part that is similar to our previous one channel part but is vastly improved. The improvements being: 16 character receiver, 16 character transmit FIFOs, watch dog timer for the receiver, mode register 0 is added, extended baud rate, over all faster bus and data speeds, programmable receiver and transmitter interrupts and versatile I/O structure. (The previous one channel part, SCC2691, is NOT being discontinued.)

FEATURES
• Member of IMPACT family: 3.3 to 5.0 volt , –40°C to +85°C and 68K for 80xxx bus interface for all devices.
• A full-duplex independent asynchronous receiver/transmitter
• 16 character FIFOs for each receiver and transmitter
• Pin programming selects 68K or 80xxx-bus interface
• Programmable data format
    – 5 to 8 data bits plus parity
    – Odd, even, no parity or force parity
    – – 1, 1.5 or 2 stop bits programmable in 1/16-bit increments
• 16-bit programmable Counter/Timer
• Programmable baud rate for each receiver and transmitter selectable from:
    – 28 fixed rates: 50 to 230.4 k baud
    – Other baud rates to 1 MHz at 16X
    – Programmable user-defined rates derived from a programmable counter/timer
    – External 1X or 16X clock
• Parity, framing, and overrun error detection
• False start bit detection
• Line break detection and generation
• Programmable channel mode
    – Normal (full-duplex)
    – Automatic echo
    – Local loop back
    – Remote loop back
    – Multi-drop mode (also called ‘wake-up’ or ‘9-bit’)
• Multi-function 7-bit input port (includes IACKN)
    – Can serve as clock or control inputs
    – Change of state detection on four inputs
    – Inputs have typically >100k pull-up resistors
    – Change of state detectors for modem control
• Multi-function 8-bit output port
    – Individual bit set/reset capability
    – Outputs can be programmed to be status/interrupt signals
    – FIFO status for DMA interface
• Versatile interrupt system
    – Single interrupt output with eight maskable interrupting conditions
    – Output port can be configured to provide a total of up to six separate interrupt outputs that may be wire ORed.
    – Each FIFO can be programmed for four different interrupt levels
    – Watch dog timer for the receiver
• Maximum data transfer rates: 1X – 1Mb/sec, 16X – 1Mb/sec
• Automatic wake-up mode for multi-drop applications
• Start-end break interrupt/status with mid-character break detect.
• On-chip crystal oscillator
• Power down mode
• Receiver time-out mode
• Single +3.3V or +5V power supply